Assemblies are known including systems to detect the presence and in particular the correct positioning of an object relative to its support in various technical fields.
In the field of measuring assemblies with measuring or checking apparatuses, more particularly, of manual comparators for dimensional and/or shape checking of mechanical pieces, it is important that the comparators are correctly positioned with respect to the relative support for example at the time when, after having performed the checking operations, the comparator is put away, or stored, by the operator or user. It is known to employ a recognition system that detects, for example by means of a mechanical switch, and indicates, for example through an indicator light or a proper message managed by electronics, the correct positioning of the comparator. This allows to reduce the idle time. Moreover, in this way the operator can have an immediate visual indication of the correct positioning, so helping to avoid accidental falls of the device due to improper placement. Similarly, in a storage structure containing a large number of comparators, the presence of a recognition system allows the operator to easily and quickly get information of the possible incorrect positioning of one or more comparators, so preventing the emission of signals of alarm and consequent loss of time spent to search the cause of the malfunction.
Recognition systems of this type are also applied to wireless comparators in combination with battery charging devices. These comparators, comprising a handle for manual use, are powered by batteries, typically housed in the handle, which, through an electric circuit comprising a number of electrical contacts, provide current to the transmission system of the comparator, the latter being normally housed in the handle, too. The wireless comparators offer far better handling features and ease of use compared to the wired comparators, but have the disadvantage that the batteries need to be replaced and/or recharged whenever they discharge. There are known different devices for charging batteries, which provide either the recharging of the batteries mounted in the comparator, or the removal of the batteries and their separate charging on suitable charging devices. Obviously, the charging of the batteries when they are embedded in the comparator is more convenient and advantageous and can be carried out by providing the comparator with appropriate electrical contacts, for example holes or sockets for pins, or contact pads, intended to be coupled to corresponding electrical contacts of an external power supply. Inductive type charging devices are also known which do not feature uncovered and exposed contacts so as to ensure operating reliability and safety for the operator. Known comparators including inductive charging systems can be placed on a proper charging base, or stand, and there they can be left for the time necessary to recharge. The correct positioning of the comparator on the stand is generally defined by bearing surfaces. Possible accidental movement between the parts, or an imprecise arrangement on the stand may prevent the proper charging. In addition, during charging, in the shop floor environment where the comparator is normally used, the comparator placed on the charging stand may undergo shocks and/or external stresses, so that the comparator may fall and break away from the charging station, causing damages and interrupting the charging process.
To ensure that the charging of the batteries takes place only when the comparator is properly arranged in relation to the charging device, recognition systems are provided. The recognition system automatically triggers the charging when the comparator is properly positioned and interrupts the charging whenever the comparator is removed from the stand or takes an incorrect position for example because of an accidental collision. These recognition systems provide, for example, to have, in addition to the transmission of power to charge the battery, a data communication to check the presence and the status of the comparator. In case of a negative response from the comparator, the power supply is not activated or is stopped. Such systems are also applicable in the industrial sector including rechargeable manual tools, such as drills, screwdrivers or other tools, and even in different sectors of activity for instance for charging the batteries of mobile phones.
This type of recognition systems requires two complex logic units, one in the charging stand and one in the removable device, that make the structure more expensive and complex and may face size problems inside the structure itself.
Other types of recognition systems are known.
The U.S. Pat. No. 4,031,449 for example, describes a battery charger with inductive coupling and comprising a proximity sensor to activate the power system when the battery to be charged is present and properly arranged. When the battery is present and properly arranged, the magnetic field generated by a primary winding arranged in the charger propagates in the secondary winding connected to the battery to be recharged and is not detected by the proximity sensor. On the contrary, when the battery is not properly coupled with the battery charger, the magnetic field passes through the proximity sensor. It is, however, necessary to maintain a minimum level of current to allow the recognition system to detect the presence of the battery when the latter is approached to the charger. The operation of the recognition system thus requires that the charging device continuously provide power to the system.
A different example of recognition system is described in U.S. Pat. No. 3,641,336 relating to an emergency electric lamp provided with a device for charging the battery. FIG. 3 of this patent shows a solution comprising a security system to interrupt the power supply when the lamp is separated from the charging device. This safety device comprises a switch of the “reed switch” type and a magnet fixed respectively to the charging device and to the lamp. When the charging device and the lamp are coupled to each other, thanks to the presence of the magnet the switch is closed and let the current pass. When instead the charging device is removed, the switch opens and prevents the passage of the current.
In general, an electromechanical element, such as the switch, in the recognition system can undergo wear problems and thus cause malfunction of the system, and makes the seal of the rechargeable device more complex and expensive.
As regards the measuring and/or checking apparatuses that are part of the assembly according to the invention, examples of manual measuring and checking apparatuses such as comparators are described in patent documents filed by the same Applicant of the present application and published with n. WO9501547A1, WO2007128805A2 and WO2010108990A1.
These comparators comprise a shell defining a handle that can be gripped by the user to handle the device.
The shell is hollow and houses electronic circuits or a board, and in some cases a position transducer and a battery to power the device.
Furthermore, each comparator has a probe with at least one movable feeler adapted to touch the workpiece to be checked. To measure a projecting element, in particular a part featuring an outer diameter, the feeler can be supported by a fork shaped element and the comparator is referred to as “fork gauge” or even “snap gauge”. If the element to be measured is a cylindrical hole or seat, the feeler is usually mounted on a cylindrical ogive or drum, and the comparator is referred to as “plug gauge”.
In a typical embodiment, the probe has a movable stem coupled to the feeler and the position transducer. Furthermore, the comparator may comprise a user interface to display information on the operation of the device. In the above-mentioned examples, the interface includes an LED that lights up to indicate that the device is on.
The comparator is also provided with a pushbutton accessible from the outside of the shell to transmit control signals to the electronic circuits including a control to acquire the measurement data detected by the transducer.
These industrial measurement systems are used widely, even though not exclusively, in the automotive industry.
From the practical point of view, the user must carry out—in his workstation—a series of measurements, one after the other, on a same complex mechanical system. For example, on a cylinder head of an engine, there are several openings and protruding parts to be measured, and only after having completed all measurements, the user gets away the cylinder head from the workstation, to receive a new cylinder head to be measures and checked.
In this context, it is noted that, normally, a workstation is equipped with a plurality of measuring and checking apparatuses, which form a work kit, that is a measuring and checking kit for the user. Typically, the various comparators differ from one another because they include different probes as far as type, size or shape are concerned.
Operatively, the user, after having gripped the comparator, positions it with the probe coupled to the mechanical part to be measured and, when he considers that the positioning of the comparator is correct, pushes the pushbutton to acquire the measurement data.
The measurement data should be further elaborated. To this end, the workstation is generally equipped with a computer provided with a display.
In some solutions, the comparator is connected to the computer via an electrical cable. In other solutions, the comparator exchanges data wirelessly with the computer, so granting greater freedom of movement to the user who handles the comparator.
The above-mentioned technological sector implies various requirements.
A requirement is to make sure that the measurement and/or checking operations are efficient and highly productive.
This means reducing the likelihood that the user makes mistakes and allowing him to work quickly, reducing to a minimum the execution time of operations that the user must carry out.
To this end, the computer of the workstation, generally, implements a guided procedure or wizard that appears on the screen of the workstation, so the user can see and follow a guided sequence of operations to be performed. For example, the wizard will suggest to the user to take a certain comparator or group of comparators for measuring a part of a particular workpiece, then it will suggest to store that comparator and to take another one for carrying out a new measurement, and so on.
This helps to reduce the number of situations in which the user performs wrong operations and increases the efficiency of work.
However, the adoption of the wizard has some limitations.
One limitation is due to the risk that the user is wrong to select the comparator suggested by the wizard.
An error of this type involves at least that some time gets lost.
Moreover, idle times remain due to a delay between the instant at which the user grasps the proper comparator and the instant in which the comparator is ready to perform the measurement.
In order to make the workstation, or the single comparator, most versatile and contain costs, typically the probe of the comparator is interchangeable with other probes.
In this regard, another need is to make particularly rapid and safe the replacement of the probe in the comparator. In this context, the known solutions, described in the above-mentioned patent documents, do not allow to properly combine the needs of connection speed, firmness of the connection and ease of adjustment of the relative angular position between the probe and the shell.
Another requirement is to make the user's work particularly easy and convenient, as regards both the reading of the data detected by the comparator upon acquisition and the handling of the comparator itself. In this context, in the solutions in use, the user reads the data detected by the comparator (for example a diameter of a seat or opening) on the screen of the workstation and, when he considers that the displayed value is stable or correct, controls the acquisition of such data by actuating the pushbutton. This is inconvenient and may cause mistakes, because the user, in order to check the data on the screen, has to turn his head and look away from the comparator that has to be firmly kept in the correct position, coupled to the mechanical piece to be measured.
It is also to be noted that the user is required to hold the comparator in various spatial orientations, depending on the position and the shape of what is to be measured. This implies that the comparator of the known examples is not ergonomic and easy to use in all situations, with particular reference to the need to maintain the comparator in the correct position and at the same time press the pushbutton.
In this light and in connection with manual gauges or comparators as the ones according to the present invention, particular importance is assumed by the ergonomics of the product. In fact, in the precision measurements it is important to arrange and firmly keep the comparator in the proper position when the measurement is acquired. In practice, the ease with which the comparator is grasped, the accessibility to the pushbutton for the acquisition of the measurement data, the convenience with which the comparator can be kept in position, the ease with which the measurement can be read are particularly relevant aspects.
Another requirement refers to the robustness and reliability of the gauge or comparator.
Such gauges are intended to be used in an industrial environment where shocks may occur and where it is common to find contaminants, in the form either of powders and of liquid. Furthermore, when the user inserts the probe in a seat and presses with his hand on the comparator to acquire the measurement, he exerts on the connection zone between the probe and the shell a force, more specifically a bending moment, which tends to break the gauge itself. For these reasons, this type of comparators is subject to particular risks of damage by mechanical stresses or of failure for the entry of contaminants.
Further to the need to protect from external agents such as liquids and powders, there is also the compelling necessity, given the different regulations in force in many countries, to ensure a high level of electromagnetic compatibility of the product. That is, it is required to ensure that, in the presence of phenomena such as electrostatic discharge (ESD) and the like, the operation of the product is not compromised, permanently or even temporary.
These needs related to the robustness and reliability, as well as electromagnetic compatibility, cannot find a fully satisfactory response in the currently available gauges.
Indeed, certain solutions of the known comparators, for example in order to allow to adjust the mutual angular position between the probe and the shell, in fact lessen the robustness of the probe.
A further need for the known comparators is to simplify the maintenance and reparability, for reasons of time and cost.
In this regard, it is noted that the comparators or gauges of the known solutions are generally not easy to assemble, for example because they imply rather complex internal electrical connections to be carried out inside the shell, which are difficult to achieve.